Neural Modeling of Social Adaptive Behaviors of Insects Yusuke Ikemoto¤, Tomohisa Fujiki¤, Kuniaki Kawabata¤¤, Hitoshi Aonuma¤¤¤, Toru Miura¤¤¤, and Hajime Asama¤ ¤RACE, The University of Tokyo ¤¤RIKEN ¤¤¤Hokkaido University 5-1-5 Kashiwano-ha, Kashiwa, 2-1 Hirosawa, Wako, Saitama, 060-0810 Sapporo, Japan Japan Japan [email protected] fikemoto, fujiki, [email protected] [email protected] [email protected] Abstract— All the life forms such as humans, animals and insects, can behave adaptively even in diverse and complex environment in various types of behaviors. Such adaptive CNCVG UQNFKGT behaviors are considered to emerge from the interaction of the body, brain, and environment, which is induced by the active P[ORJ RTGUQNFKGT mobility of the cognitive subject. Base on the consideration, we call the intelligence for generating adaptive motor function CVKQP mobiligence. The Mobiligence project started from 2005 as s five-years project to understand the mechanisms for the HHGTGPVK generation of intelligent adaptive behaviors. In the group C TGRTQFWEVKQP UVCVKQPCT[OQNV YQTMGT of the mobiligence project, we focus on mechanism whereby RUGWFGTICVG UQNFKGTFK a cognitive subject adapt to other cognitive subjects or its NCTXC society. In this paper, some neural models of the social adaptive behaviors of insects are introduced, such as on proportion GII control in caste differentiation of termites, and on behavior selection in fighting behaviors of male crickets. I. INTRODUCTION Fig. 1. Termite caste differentiations in termite Hodotermopsis sjostedti Living organisms adaptively select behavior through the interactions with their society in real time. Their behaviors generate sociality and the behaviors are determined by social- ity. We call the behaviors selections related in society ”social adaptive behaviors” in the group C of the Mobiligence project. The plasticity plays important and fundamentally roles in adaptation behaviors. This is attributable to various mediators such as neuromodulators in brain, hormones in the body, and pheromones in group as superorganism like colony. If we can know the principle of social adaptations, it can be applied to design methodology for autonomous robotic systems. Fig. 2. Male crickets fighting Just how fragmented information obtained from analytical results operates in an actual system remains unclear, and we believe it is important to alternately repeat synthetic and 1). The function differentiation process is seemingly regarded analytical approaches in which a dynamic hypothetical model as transition from a homogeneous state to a heterogeneous is simulated based on information from static physiological one in multibody system against the second law of thermo- experiments and to verify the results obtained in further dynamics. Although the behaviors of particle in equilibrium physiological experiments[1]. Even now, we have a lot of systems have been discussed enough, nonequilibrium open things to learn from efficient insect behaviors because insects systems have not been systematized from the perspective are well-researched compared with vertebrate animals. It is of thermodynamics yet. One reason seems to be that the wise to determine the equations of evolution of systems with principle must be modeled by enforced approximation of generality from the mutual integration chains. Especially, phenomenon and the experiment data because potentials are we treat the termite caste differentiation and cricket fighting not expressly given such as mechanical energy and free behaviors as example of social adaptive behaviors. energy. In termite example, self-organized proportion control is In cricket example, we focus the time evolution of some treated as functional differentiations of individuals in a sys- neuromodulator titers in the brain for behavior selection on tem according to environment conditions and given tasks(Fig. the specific behaviors ,cricket fighting(Fig. 2). In behavior selection, nitric oxide (NO) is thought to function as a neuromodulator (NM) for extracting a specific behavior program from polymorphic circuits in the brain and that the NO/cyclic guanosine monophosphate (cGMP) cascade plays an important role[2]. In this paper, we introduce the study examples of termite Vb caste differentiation modeling in section II-IV and cricket Potential Vw behavior selection modeling in section V-VIII. Finally, we conclude in section VIII. Vs II. TERMITE CASTE DIFFERENTIATION bw b bs The termite (Order Isoptera, Class Insecta) is categorized Hormone ui into a eusocial insect that lives in a group based on kinship and forms a colony with a certain size. In a termite colony, Fig. 3. Landscape by potential Vi. there are several castes called worker, soldier, nymph, king and queen in addition to immature larvae. The developmental pathways to caste differentiation are diverse from species by the application of juvenile hormone and its analogues to species [3][4][5][6][7][8]. Even though each individual [12][19][20]. In a colony level, it is reported that Reticuliter- has the similar genetic background, they present different mes flavipes adaptively changes the caste ratio according phenotypes through anatomical specialization according to to season[13]. In addition, there are important reports in the castes [9][10][11]. other eusocial insects, in which colonies increase the soldier Among the various castes, soldier castes is a peculiar proportion when they confront competitors, predators or one because soldiers are completely sterile and perform intruders[21][22][23]. Termite colony generally seems to altruistically to attack against predators or intruders. The control the caste ratio precisely, depending on the environ- control of soldier ratio in a colony is an important regulatory ment conditions without global controls that means controls system in the termite societies[12][13]. In addition, there is determined by congenitally genetic informations[24][25]. a special stage called ”presoldier” in the course of soldier differentiation. Soldiers are normally induced from workers III. MODELING DIFFERENTIATION PROCESS via presoldier stage through two molting events. Presoldiers The mathematical principle model is constructed based can be regarded as the system buffer for the early adaptations on biological reports and the assumption in section II. In of social systems as shown in figure 1. It is mainly thought order to discuss the basic caste differentiation control mech- that such altruistic behaviors have been evolved by kin anism through one kind of pheromone, bare essentials of selection[14]. mathematical model is expressed. In fact, the states of the The caste differentiation had been acquired as the adap- system consist of group of ui that is amount of hormone tation for the extremely precise social behaviors and self- in individual i and the genotype are expressed by one organization. The multiple phenotypes of individuals and dimensional potential function. The genotype is described the caste ratio controls can be respectively regarded as the as extremal values of the potential function. In this model, adaptations in micro and macro level. Both of the adaptations therefore, the dynamics of internal hormone are on bistable must work out under coherent relations between them. It is potential because differentiations between two kinds of caste important for exploring the strategy of eusocial insects to are focused. The equations of evolution of ui are as follows: consider information cycle between macro and micro layers. As Luscher¨ reported the following working thesis obtained ¶u ¶V N i = ¡ i ¡ D ∑ (w u ¡ d) (1) by several biological experiments, the caste differentiation ¶ ¶ i i j j t ui j=1; j=6 i seems to be accomplished under the pheromonal control ¶V which is not transferred by diffusion in air of chemical sub- i ¡ ¡ ¡ ¶ = (ui bw)(ui b)(ui bs); (2) stances, but through trophallaxis behaviors in which colony ui members exchange food matrials from mouth to mouth[15]. where ¶Vi=¶ui is given as show in figure 3 that describe However, there is the hypothesis that caste ratio is also the shape of genotype potential. N means the constant controlled by exocrine volatiles[16][17]. For example, in Na- number of individuals in the colony. Vw, Vs and Vb are sutitermitinae, defense substances function as the chemical the constant number of potential when ui = bw，ui = bs pheromones that inhibit the soldier production[18]. However, and ui = b, respectively. bw，bs and b are constant, those the effective pheromonal substances are not identified yet. are evolutionarily-conserved, so that they determine optimal In order to realize the caste differentiation processes, it is caste ratio. Di is the stochastic variable that mean the number necessary to approach from both physiological mechanisms of contacts among individuals over time. wi j is a stochastic ∑N in an individual and system methodology in the colony variable and satisfies j=1; j=6 i wi j = 1 at any time, meaning level. In an individual level, several researches succeeded the frequency of contact between individuals i and j. d is to find the methods of induction from workers to soldiers also the constant number determining the optimum caste ratio which is evolutionarily-conserved. The equations of evolution (1) include stochastic variables depending on both G= - 0.1 a average number of contacts and which the individual has contacts with other one. The potential of activation for state G=0 transition from worker to soldier depend on Vb ¡ Vw. The G=0.1 eq fluctuations are needed for transitions to climb the potential P of activation. In order to separate stochastic factor from average amount, Di and wi j are replaced in the following equations: c Di = Di + Ri(t) (3) c wi j = wi j + ri j(t) (4) uj hRi(t1)Ri(t2)i = 2MDd(t1 ¡t2) (5) hr (t )r (t )i = 2M d(t ¡t ); (6) Fig. 4. Transition of probability distributions Peq at bw = 0:1, bs = 0:9, i j 1 i j 2 w 1 2 c b = 0:4, M = 0:005, MD = 0:01 and Di = 0:01.